Multiple choice

In an examination, average marks obtained by the girls of a class are 85 and the average marks obtained by the boys of the same class are 87. If the girls and boys are in the ratio 4 : 5, average marks of the whole class (approx.) are closest to

  1. 86.4

  2. 86.5

  3. 85.9

  4. 86.1
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D Correct answer
Explanation

Weighted average = (4 * 85 + 5 * 87) / (4 + 5) = (340 + 435) / 9 = 775 / 9 = 86.11.

AI explanation

Using the method of weighted average, assume there are 4 girls and 5 boys. The weighted sum is (4 multiplied by 85) plus (5 multiplied by 87), which equals 340 plus 435, giving a total of 775. The total number of students is 4 plus 5, which is 9. The overall average is 775 divided by 9, which equals 86.11, making the closest value 86.1.

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